Backpack



FIG. 1 is a perspective view of a backpack showing my new design;

FIG. 2 is another perspective view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a rear elevational view thereof;

FIG. 5 is a left side elevational view thereof;

FIG. 6 is a right side elevational view thereof;

FIG. 7 is a top plan view thereof; and,

FIG. 8 is a bottom plan view thereof.

The short thick dash-dash broken lines in the drawings depict stitching that forms part of the claimed design. The long thin broken lines in the drawings depict portions of the backpack that form no part of the claimed design. 

CLAIM The ornamental design for a backpack, as shown and described. 